In a pipe coupling which employs a poppet valve for opening and closing a fluid passage, a valve holding member is used, which has a hub part through which a valve stem of the poppet valve passes, and a plurality of arm parts extending radially outwardly from the hub part and firmly engaging with the inner surface of the fluid passage to retain the hub part in the center of the fluid passage. The valve is set such that a valve head thereof is pressed against a valve seat formed on the inner surface of the fluid passage by means of a coil spring disposed around the valve stem and between the hub part and the valve head.
The present applicant has filed an application related to a valve holding member characterized in that the valve holding member is made of a single sheet metal (Japanese Examined Utility Model Publication No. S55-33091). This valve holding member has an advantage of being fabricated at low cost. However, due to its low stiffness, the valve holding member is mainly used for low-pressure and small-diameter pipe couplings, in which a biasing force of a coil spring acting on a valve is small.
However, there is a need for a valve holding member made of a sheet metal which has a high stiffness for withstanding a large spring biasing force so as to be used for high-pressure and large-diameter pipe couplings. In order to increase stiffness, there is a method in which the thickness of the sheet metal and/or the width of arm parts are increased. However, if a thick sheet metal is used, the arm parts lacks resilience, whereby it becomes difficult to insert the valve holding member into a pipe coupling. Further, if the arm parts are made wider, a flow resistance of the fluid passage is made greater.
Conventionally, as a high-strength valve holding member for high-pressure and large-diameter pipe couplings, there have been used block-type valve holding members (which are sufficiently thick in the fluid passage direction of a pipe coupling) as disclosed in Japanese Unexamined Utility Model Publication No. 59-105683, and ring-type valve holding members (in which arm parts are connected together by means of a ring) as disclosed in Japanese Unexamined Utility Model Publication No. 51-98825. In fabricating the above valve holding members, however, it is necessary to machine a blank material or to mold powder metal. As a result, the fabricating cost and weight of the products increase compared to a sheet metal valve holding member which can be fabricated by pressing.
It is an object of the present invention to provide a sheet metal valve holding member which has reinforcing structures to increase its stiffness, thereby allowing them to be used for high-pressure and large-diameter pipe couplings.